Have a rousing effect on (5)
I believe the answer is:
waken
'have' is the definition.
The answer and definition can be both related to bodily activities as well as being verbs in their base form.
Perhaps there's a link between them I don't understand?
'a rousing effect on' is the wordplay.
'a rousing' becomes 'n' (I can't justify this - if you can you should believe this answer much more).
'effect' becomes 'wake' (wake is a kind of effect).
'on' means one lot of letters go next to another.
'n' put after 'wake' is 'WAKEN'.
Can you help me to learn more?
(Other definitions for waken that I've seen before include "Rouse from sleep" , "Come round" , "Stir yourself" , "Arouse from sleep" .)