Old one isn't truthful - time to be most ingratiating (7)
I believe the answer is:
oiliest
'most ingratiating' is the definition.
Both the answer and definition are superlative adjectives. Perhaps they are linked in a way I don't understand?
'old one isn't truthful time' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'one' becomes 'i' (Roman numeral).
'isn't truthful' becomes 'lies' (I've seen this in another clue).
'time' becomes 't' (abbreviation).
'o'+'i'+'lies'+'t'='OILIEST'
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for oiliest that I've seen before include "Most unctuous" , "Most flattering" , "Most greasy" .)