More than a foot behind (5)
I believe the answer is:
after
'behind' is the definition.
(I've seen this in another clue)
'more than a foot' is the wordplay.
I cannot quite see how this works, but
'a' is found in the answer.
'foot' could be 'ft' (synonyms) and 'ft' is found in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for after that I've seen before include "Coming later in time" , "Searching for" , "In pursuit of, behind" , "Following, consequent to" , "In honour of" .)