Strange guys start toying with a left-over bit (7)
I believe the answer is:
oddment
'bit' is the definition.
(an oddment is a bit or fragment)
'strange guys start toying with a left-over' is the wordplay.
'strange guys' becomes 'men' (guy can mean a man. I am not sure about the 'strange' bit.).
'start' suggests taking the first letters.
'with' is a charade indicator (letters next to each other).
'a left over' becomes 'odd' (I've seen this before).
The first letter of 'toying' is 't'.
'men'+'t'='ment'
'ment' put after 'odd' is 'ODDMENT'.
Can you help me to learn more?
(Other definitions for oddment that I've seen before include "An isolated article, something left over" , "One of a broken set" , "spare part?" , "Piece left over, no match" , "Left over item" .)