He’ll have a stab at it (5)
I believe the answer is:
lance
'he'll' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'a stab at it' is the wordplay.
I cannot really see how this works, but
'a' could be 'an' and 'an' is found in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
This explanation may well be incorrect...
'have' is the link.
Can you help me to learn more?
(Other definitions for lance that I've seen before include "Long, pointed weapon (5)." , "One like pike" , "Knightly weapon" , "Pierce (a boil)" , "Long weapon; prick" .)