Titan with note changed for ear (9)
I believe the answer is:
attention
'ear' is the definition.
(I've seen this in another clue)
'titan with note changed' is the wordplay.
'with' means one lot of letters go next to another.
'changed' indicates an anagram.
'titan' put after 'note' is 'notetitan'.
'notetitan' with letters rearranged gives 'ATTENTION'.
'for' acts as a link.
(Other definitions for attention that I've seen before include "For coverage" , "What students must pay" , "Keen students pay this" , "Applying the mind, mental concentration" , "notice" .)