Specialists accepting one group of workers for trials (11)
I believe the answer is:
experiments
'trials' is the definition.
(I've seen this before)
'specialists accepting one group of workers' is the wordplay.
'specialists' becomes 'experts' (I've seen this before).
'accepting' indicates putting letters inside.
'one group of' becomes 'i' (I've seen this in other clues).
'workers' becomes 'men' (man is a kind of worker).
'i'+'men'='imen'
'experts' enclosing 'imen' is 'EXPERIMENTS'.
'for' acts as a link.
(Another definition for experiments that I've seen is " Trials".)