Muscleman buried by old criminal (11)
I believe the answer is:
bodybuilder
'muscleman' is the definition.
(I've seen this before)
'buried by old criminal' is the wordplay.
'criminal' is an anagram indicator.
'buried'+'by'+'old'='buriedbyold'
'buriedbyold' anagrammed gives 'BODYBUILDER'.
(Other definitions for bodybuilder that I've seen before include "Person working on strengthening muscles" , "Muscleman" , "Person enlarging their muscles" , "One developing muscles through exercise" , "Muscular poser" .)