American four, returning, reportedly steered clear of bridge (7)
I believe the answer is:
viaduct
'bridge' is the definition.
(I know that viaduct is a type of bridge)
'american four returning reportedly' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'four' becomes 'IV' (Roman numerals).
'returning' is a reversal indicator.
'reportedly' becomes 'duct' (I can't justify this - if you can you should give a lot more credence to this answer).
'a'+'iv'='aiv'
'aiv' written backwards gives 'via'.
'via'+'duct'='VIADUCT'
'steered clear of' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for viaduct that I've seen before include "Long bridge over land" , "Type of bridge" , "Kind of road over a road" , "Road/rail bridge" , "Rail bridge over valley" .)