Celebrity Madrid coach suffering 1-0 reversal during first half (7)
I believe the answer is:
someone
'celebrity' is the definition.
(I've seen this before)
'during first half' is the wordplay.
'during' becomes 'some' (I can't explain this - if you can you should give a lot more credence to this answer).
'first' means one lot of letters go next to another.
'half' becomes 'one' (I have seen 'Half of two ' mean 'one' so perhaps 'half' could also mean 'one').
'some'+'one'='SOMEONE'
'madrid coach suffering 1-0 reversal' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
(Other definitions for someone that I've seen before include "An unknown person" , "Important person" , "Celebrity" , "A person (maybe of importance)" , "Unspecified human being" .)