Babel building (5)
I believe the answer is:
'babel building' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tower that I've seen before include "Tall feature of Blackpool" , "Stand very high (over)" , "Pisa has a leaning one" , "Wrote (anag.)" , "Rise to great height" .)