Small group allowed on tour (7)
I believe the answer is:
triplet
'small group' is the definition.
(I've seen this before)
'allowed on tour' is the wordplay.
'allowed' becomes 'let' (I've seen this before).
'on' says to put letters next to each other.
'tour' becomes 'trip' (I've seen this in other clues).
'let' after 'trip' is 'TRIPLET'.
(Other definitions for triplet that I've seen before include "One of three at the same birth" , "Group of three equal notes" , "one arriving with two others" , "One of several arriving together" , "One of a small group" .)