Compensation relating to a frock (7)
I believe the answer is:
redress
'compensation' is the definition.
(redress is a kind of compensation)
'relating to a frock' is the wordplay.
'relating to' becomes 're' (re can mean with regards to).
'a frock' becomes 'dress' (synonyms).
're'+'dress'='REDRESS'
(Other definitions for redress that I've seen before include "Pay" , "Correct" , "Set right - compensation" , "Prepare again - satisfaction" , "remedy" .)