Rex comes off wagon at saloon opening times! (4)
I believe the answer is:
days
'opening times' is the definition.
'days' can be an answer for 'times' (day is a unit of time). I'm unsure of the 'opening' bit.
'rex comes off wagon at saloon' is the wordplay.
'rex' becomes 'R' (abbreviation e.g. GR=George Rex, King George).
'comes off' suggests deleting specific letters.
'wagon' becomes 'dray' (dray is a kind of wagon).
'at saloon' becomes 's' (I can't explain this - if you can you should believe this answer much more).
'dray' with 'r' removed is 'day'.
'day'+'s'='DAYS'
Can you help me to learn more?
(Other definitions for days that I've seen before include "See 7 and 18" , "Time period(s)" , "Twenty-four hour periods" , "Units of time" , "24-hour periods" .)