Strange fellows having first bit of trouble in scrap (7)
I believe the answer is:
oddment
'scrap' is the definition.
('oddment' can be a synonym of 'scrap')
'strange fellows having first bit of trouble' is the wordplay.
'strange' becomes 'odd' (I've seen this before).
'fellows' becomes 'men' (I've seen this before).
'having' is a charade indicator (letters next to each other).
'first bit of' suggests taking the first letters.
The initial letter of 'trouble' is 't'.
'odd'+'men'+'t'='ODDMENT'
'in' is the link.
(Other definitions for oddment that I've seen before include "Left over item" , "Leftover item" , "An isolated article, something left over" , "Piece left over, no match" , "a bit spare" .)