Alpha male causing scrap (4)
I believe the answer is:
atom
'scrap' is the definition.
(thesaurus)
'alpha male' is the wordplay.
'alpha' becomes 'a' (phonetic alphabet: alpha, bravo, charlie etc.).
'male' becomes 'tom' (I've seen this before).
'a'+'tom'='ATOM'
'causing' acts as a link.
(Other definitions for atom that I've seen before include "A tiny particle of matter with a big bang" , "Particle; molecule" , "Neutron and proton" , "Small amount of matter" , "Something very small perhaps" .)