Crossbreed having day with gang leader, about 50 (7)
I believe the answer is:
mongrel
'crossbreed' is the definition.
(I've seen this in another clue)
'day with gang leader about 50' is the wordplay.
'day' becomes 'mon' (abbreviation for Monday).
'with' is a charade indicator (letters next to each other).
'gang leader about' becomes 'gre' (I am not sure about this - if you are sure you should believe this answer much more).
'50' becomes 'l' (Roman numeral).
'mon'+'gre'+'l'='MONGREL'
'having' is the link.
Can you help me to learn more?
(Other definitions for mongrel that I've seen before include "Mixed-breed dog" , "unlike well-bred setter, say" , "Dog of mixed breed" , "Non-pedigree" , "Cur" .)