Beg for a pad to put round a leg that's not good (5)
I believe the answer is:
plead
'beg' is the definition.
(I've seen this in another clue)
'pad to put round a leg that's not good' is the wordplay.
'to put round' is an insertion indicator.
'that's not' is a deletion indicator ('that has not' as in 'that doesn't have').
'good' becomes 'g' (abbreviation).
'leg' with 'g' removed is 'le'.
'pad' going around 'le' is 'PLEAD'.
'for a' is the link.
(Other definitions for plead that I've seen before include "Respond to charge" , "Beg, implore" , "Appeal humbly (to)" , "Present an argument in court" , "Argue (for a cause)" .)