Research put into model vehicle design (5)
I believe the answer is:
delve
'research' is the definition.
(I've seen this before)
'into model vehicle design' is the wordplay.
'into' says the answer is hidden in the clue.
'DELVE' can be found hidden inside 'model vehicle design'.
'put' is the link.
(Other definitions for delve that I've seen before include "Dig up - search" , "probe deeply" , "Rummage deep (in)" , "Dig deep" , "Burrow" .)