In deluge I recollected recommendation (9)
I believe the answer is:
guideline
'recommendation' is the definition.
'in deluge i recollected' is the wordplay.
'recollected' indicates an anagram (letters recollected and rearranged).
'in'+'deluge'+'i'='indelugei'
'indelugei' anagrammed gives 'GUIDELINE'.
(Other definitions for guideline that I've seen before include "General piece of advice" , "General item of advice" , "Rule of thumb -- need Luigi (anag)" , "Directing rule or principle" , "Advice on general policy" .)