Check transport during time off work (9)
I believe the answer is:
restraint
'check' is the definition.
(I've seen this before)
'transport during time off work' is the wordplay.
'transport' becomes 'train' (train is a kind of transport).
'during' is an insertion indicator.
'time off work' becomes 'rest' (rest time).
'train' put into 'rest' is 'RESTRAINT'.
(Other definitions for restraint that I've seen before include "Control, restriction, curtailment" , "Restriction, limit" , "Controlling measure" , "Self-discipline" , "Reserve" .)