Follow one on the road to the gallery (7)
I believe the answer is:
imitate
'follow' is the definition.
(thesaurus)
'one on the road to the gallery' is the wordplay.
'one' becomes 'i' (Roman numeral).
'on' means one lot of letters go next to another.
'the road' becomes 'mi'.
'to the gallery' becomes 'tate' (I've seen this before).
'i'+'mi'+'tate'='IMITATE'
(Other definitions for imitate that I've seen before include "Take as a model" , "'Ape, copy (7)'" , "I tame it (anag)" , "Mock" , "Copy, simulate" .)