Recruit occasionally seen before short turn (5)
I believe the answer is:
enrol
'recruit' is the definition.
(I know that recruit can be written as enrol)
'occasionally seen before short turn' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
'before short' becomes 'lor' (I can't justify this - if you can you should believe this answer much more).
'turn' says the letters should be written in reverse.
The alternating letters of 'seen' are 'en'.
'lor' back-to-front is 'rol'.
'en'+'rol'='ENROL'
Can you help me to learn more?
(Other definitions for enrol that I've seen before include "Recruit" , "Loner inclined to join in" , "Record" , "register for classes" , "Join up, sing on" .)