Answer with point that's pertinent (3)
I believe the answer is:
'pertinent' is the definition.
(I've seen this before)
'answer with point' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'with' means one lot of letters go next to another.
'point' becomes 'pt' (**).
'that's' is the link.
(Other definitions for apt that I've seen before include "clever" , "Ready to learn" , "Fit, suitable" , "Tap (anag.)" , "Suitable; quick to learn" .)