Strongly affected by having to join up? (9)
I believe the answer is:
impressed
'strongly affected' is the definition.
'impressed' can be an answer for 'affected' (similar in meaning). I'm not sure about the 'strongly' bit.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for impressed that I've seen before include "Favourably influenced" , "Forced into service - unlikely to forget it!" , "Markedly affected" , "printed word?" , "Greatly inspired" .)