Sports obsessive's heart set on Collingwood (5)
I believe the answer is:
spies
'collingwood' is the definition.
I can't tell whether this defines the answer.
'sports obsessive's heart set on' is the wordplay.
'sports' becomes 'p' (I can't justify this - if you can you should give a lot more credence to this answer).
'heart' means to look at the middle letters.
'set' is an anagram indicator (instruction to set the letters).
'on' indicates putting letters inside (as in clothing 'on' a person).
The centre of 'obsessives' is 'essi'.
'essi' is an anagram of 'sies'.
'p' going into 'sies' is 'SPIES'.
Can you help me to learn more?
(Other definitions for spies that I've seen before include "Snoops" , "Undercover agents" , "Eg, CIA" , "Double agents" , "Secret agents" .)