राजा च प्रशंसायाम्

Operational rule vidhi

The word राजन् optionally retains its original accent after a profession-denoting noun when praise is expressed.

Word by word (padaccheda)

Substitute / term राजा prathamā · ekavacanaIndeclinable च avyayaRight context प्रशंसायाम् saptamī · ekavacana

Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.
Indeclinable An avyaya such as च "and", वा "optionally", न "not".
Right context Saptamī (7th case): "when X follows", the operation applies to what precedes (1.1.66 तस्मिन्निति निर्दिष्टे पूर्वस्य). Also a condition or domain ("in the sense of").

Full reading

राजा च प्रशंसायाम्

Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.

Commentary

The word राजन् optionally retains its original accent after a profession-denoting noun when praise is expressed.
Thus रा꣡जनापितः or राजनापितः꣡, रा꣡जकुलालः or राजकुलालः꣡ "A royal barber i. e. a skillful barber or one fit to serve the king even" &c. It may be either a Karmadharaya or a Genitive compound. Why do we say 'राजन्'? Observe परमनापितः ॥ Why do we say 'when denoting praise'? Observe राजनापितः꣡ 'king's barber'. Why do we say 'a professional man'? Observe राजहस्ती 'a royal elephant'.

Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.