All by myself and, oh, need to get jiggy! (3-6)
I believe the answer is:
one-handed
'all by myself' is the definition.
(one-handed can mean involving only one person)
'and oh need to get jiggy' is the wordplay.
'to get jiggy' indicates an anagram (letters jig or dance around).
'and'+'oh'+'need'='andohneed'
'andohneed' anagrammed gives 'ONE-HANDED'.
(Other definitions for one-handed that I've seen before include "very short of staff?" , "Not fully getting to grips with things" .)