Check design of trainers (8)
I believe the answer is:
restrain
'check' is the definition.
(restraining is a kind of checking)
'design of trainers' is the wordplay.
'design of' indicates anagramming the letters (I've seen this in other clues).
'trainers' anagrammed gives 'RESTRAIN'.
(Other definitions for restrain that I've seen before include "Keep back" , "Limit" , "bar" , "stay" , "Keep under control" .)