Strong macho types kept in check (8)
I believe the answer is:
vehement
'strong' is the definition.
(thesaurus)
'macho types kept in check' is the wordplay.
'macho types' becomes 'hemen'.
'kept in' indicates putting letters inside.
'check' becomes 'vet' (I've seen this before).
'hemen' inserted within 'vet' is 'VEHEMENT'.
(Other definitions for vehement that I've seen before include "Showing strong feeling, intense in speech" , "Forceful and with full conviction" , "Showing strong feeling, like even them" , "Vigorously emphatic" , "Irish symbol" .)