Measure uncompleted turn and record (5)
I believe the answer is:
enrol
'record' is the definition.
(I know this)
'measure uncompleted turn' is the wordplay.
'measure' becomes 'en' (typographical measure).
'uncompleted' becomes 'lor' (I can't justify this - if you can you should give a lot more credence to this answer).
'turn' is a reversal indicator.
'lor' back-to-front is 'rol'.
'en'+'rol'='ENROL'
'and' acts as a link.
(Other definitions for enrol that I've seen before include "Register (as student)" , "Sign on, register" , "Bring into service" , "Register officially" , "Sign on, being a loner" .)