Miner tried to keep motionless (5)
I believe the answer is:
inert
'motionless' is the definition.
(thesaurus)
'miner tried to keep' is the wordplay.
'to keep' indicates a hidden word.
'INERT' can be found hidden inside 'miner tried'.
(Other definitions for inert that I've seen before include "Lacking vigour, inactive" , "Not chemically reactive" , "Disinclined to move" , "Indolent - unreactive" , "Unmoving" .)