Timely pro, one put to work (9)
I believe the answer is:
opportune
'timely' is the definition.
(similar in meaning)
'pro one put to work' is the wordplay.
'to work' indicates an anagram (letters worked into a new order).
'pro'+'one'+'put'='prooneput'
'prooneput' is an anagram of 'OPPORTUNE'.
(Other definitions for opportune that I've seen before include "Timely, advantageous moment" , "fit" , "Of time, suitable or favourable" , "in place" , "Appropriate" .)