To gain a companion, a cranky thing to do? (5)
I believe the answer is:
winch
'a cranky thing to do?' is the definition.
I can't judge whether this defines the answer.
'to gain a companion' is the wordplay.
'to gain' becomes 'win' ('win' can be a synonym of 'gain').
'a companion' becomes 'ch' (Companion of Honour).
'win'+'ch'='WINCH'
Can you help me to learn more?
(Other definitions for winch that I've seen before include "Pull up" , "Hauling/lifting device" , "Hoist" , "Hauling or lifting device" , "Winding device" .)