A number could be here after tea (5)
I believe the answer is:
three
'a number' is the definition.
(three is a number)
'could be here after tea' is the wordplay.
'could be' is an anagram indicator.
'after' means one lot of letters go next to another.
'tea' becomes 't' (I've seen this in other clues).
'here' anagrammed gives 'hree'.
'hree' put after 't' is 'THREE'.
(Other definitions for three that I've seen before include "... number of his "Steps to Heaven"" , "A crowd, you might say" , "Number constituting a crowd?" , "Start to count back, briefly" , "Amount in a trio" .)