Don't give up in gym initially restricted by band aid (7)
I believe the answer is:
Here is my best explanation:
'band aid' is the definition.
'don't give up in gym initially restricted' is the wordplay.
'don't give up' becomes 'last' (I can't justify this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'gym' becomes 'pe'.
'initially' suggests taking the first letters.
The initial letter of 'restricted' is 'r'.
'last' placed into 'pe' is 'plaste'.
'by' is the link.
(Other definitions for plaster that I've seen before include "Smooth mixture to cover walls", "____ of Paris", "Material applied to walls", "One to cover wall, wound", "Spread", "Stucco", "Medical dressing", "Wall finish - protection for cut", "A paste; a dressing" and "Render (walls)".)