Tell of tiny change (6)
I believe the answer is:
notify
'tell' is the definition.
(I've seen this before)
'of tiny change' is the wordplay.
'change' indicates an anagram.
'of'+'tiny'='oftiny'
'oftiny' is an anagram of 'NOTIFY'.
(Other definitions for notify that I've seen before include "Formally advise" , "Formally tell" , "Formally inform" , "alert" , "Declare" .)