Soldiers (male) bitten by sort of bear’s tooth (8)
I believe the answer is:
premolar
'tooth' is the definition.
(I know that premolar is a type of tooth)
'soldiers male bitten by sort of bear's' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'male' becomes 'm' (common abbreviation).
'bitten by' is an insertion indicator (I've seen this in other clues).
'sort of bear' becomes 'polar' ().
're'+'m'='rem'
'rem' inserted inside 'polar' is 'PREMOLAR'.
(Other definitions for premolar that I've seen before include "Tooth -- real romp (anag)" , "Type of tooth" , "Grinder" .)