Male lead is husband, I'm thinking, with nothing on (4)
I believe the answer is:
hero
'male lead' is the definition.
(the male lead in a story)
'husband i'm thinking with nothing on' is the wordplay.
'husband' becomes 'h'.
'i'm thinking' becomes 'er' (expression used when hesitating).
'with' is a charade indicator (letters next to each other).
'nothing on' becomes 'o' (I've seen this in other clues).
'h'+'er'+'o'='HERO'
'is' is the link.
(Other definitions for hero that I've seen before include "Principal boy" , "Leander's suitor" , "Leander's lover - a person of courage" , "Admired champion" , "Conqueror" .)