Top alternative to taxi rank? (7)
I believe the answer is:
bustier
'top alternative' is the definition.
'bustier' can be an answer for 'top' (I've seen this before). I am not certain of the 'alternative' bit.
'taxi rank?' is the wordplay.
'taxi' becomes 'bus' (I can't explain this - if you can you should give a lot more credence to this answer).
'rank?' becomes 'tier' (tier is a kind of rank).
'bus'+'tier'='BUSTIER'
'to' acts as a link.
(Other definitions for bustier that I've seen before include "For a lady, top" , "Heavier up top!" , "to climb in to tight clothing" , "Close-fitting, strapless top without sleeves" .)