Have another go on model railway (5)
I believe the answer is:
retry
'have another go' is the definition.
(I've seen this before)
'on model railway' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'model' becomes 't' (Ford Model T car).
'railway' becomes 'ry' (abbreviation for railway).
're'+'t'+'ry'='RETRY'
(Other definitions for retry that I've seen before include "Advice following failure, initially" , "Put on trial again" , "Hear (a case) again" , "take second opinion on case" , "Have another go" .)