Rough during performance that involves old flame (7)
I believe the answer is:
inexact
'rough' is the definition.
('inexact' can be similar in meaning to 'rough')
'during performance that involves old flame' is the wordplay.
'during' becomes 'in' (I've seen this in other clues).
'performance' becomes 'act' (act is a kind of performance).
'that involves' indicates putting letters inside.
'old flame' becomes 'ex' (I've seen this in other clues).
'in'+'act'='inact'
'inact' placed around 'ex' is 'INEXACT'.
(Other definitions for inexact that I've seen before include "estimated?" , "Vague" , "Fuzzy, muddled" , "Nice tax (nag.)" , "Not precise, approximate" .)