Helped firm to get involved in under-age representation (10)
I believe the answer is:
encouraged
'helped' is the definition.
(I've seen this before)
'firm to get involved in under-age representation' is the wordplay.
'firm' becomes 'co' (a firm is a company).
'to get involved in' is an insertion indicator.
'representation' indicates anagramming the letters.
'under'+'age'='underage'
'underage' is an anagram of 'enuraged'.
'co' inserted into 'enuraged' is 'ENCOURAGED'.
(Other definitions for encouraged that I've seen before include "helped" , "Heartened" , "Inspired with confidence" , "Urged" .)