Outline argument in favour of data collection (7)
I believe the answer is:
profile
'outline' is the definition.
(thesaurus)
'argument in favour of data collection' is the wordplay.
'argument in favour of' becomes 'pro' (as in pros and cons).
'data collection' becomes 'file' (I can't explain this - if you can you should give a lot more credence to this answer).
'pro'+'file'='PROFILE'
Can you help me to learn more?
(Other definitions for profile that I've seen before include "record" , "Side view of face" , "View from one side" , "In which one may be photographed" , "Side view; portrait in words" .)