Helping stop rail strike? That's foolish (10)
I believe the answer is:
irrational
'foolish' is the definition.
(thesaurus)
'helping stop rail strike?' is the wordplay.
'helping' becomes 'ration' (a ration is a serving or helping).
'stop' means one lot of letters goes inside another (stopping can mean blocking a gap).
'strike?' is an anagram indicator (I've seen 'striking' mean this ('strike' can mean 'hit' or 'disrupt')).
'rail' with letters rearranged gives 'iral'.
'ration' placed into 'iral' is 'IRRATIONAL'.
'that's' acts as a link.
(Other definitions for irrational that I've seen before include "Crazy" , "Not logical" , "making no sense" , "Illogical" , "nuts" .)