Baron, perhaps, provided with sword is beset by extremes of laughter (4,4)
I believe the answer is:
'baron perhaps' is the definition.
(I know that baron is a type of life peer)
'provided with sword is beset by extremes of laughter' is the wordplay.
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'with' is a charade indicator (letters next to each other).
'sword' becomes 'epee' (sword used in fencing).
'is beset by' is an insertion indicator ('beset' could historically mean 'cover').
'extremes of' says to hollow out the word (remove centre letters) (only the letters at the extremes of the word).
'laughter' with its centre taken out is 'lr'.
'ifepee' placed into 'lr' is 'LIFE PEER'.
(Other definitions for life peer that I've seen before include "House of Lords appointee" , "Noble whose title cannot be inherited" , "One's entitled" , "One whose title lapses at death" , "noble always" .)