Solitary type, fellow struggling to carry on (4,4)
I believe the answer is:
lone wolf
'solitary type' is the definition.
(I've seen this before)
'fellow struggling to carry on' is the wordplay.
'struggling' indicates an anagram.
'to carry' means one lot of letters goes inside another.
'fellow' with letters rearranged gives 'lewolf'.
'lewolf' going around 'on' is 'LONE-WOLF'.
(Other definitions for lone wolf that I've seen before include "Solitary operator" , "He likes to operate by himself" , "Solitary person" , "one preferring his own company" , "One acting singly" .)