Leaden pots equally oleaginous (6)
I believe the answer is:
greasy
'oleaginous' is the definition.
(synonyms)
'leaden pots equally' is the wordplay.
'leaden' becomes 'grey' (synonyms).
'pots' means one lot of letters goes inside another (pot can mean to contain).
'equally' becomes 'as' (synonyms).
'grey' enclosing 'as' is 'GREASY'.
(Other definitions for greasy that I've seen before include "'Fatty, oily (6)'" , "Oily in manner, covered with lubricant" , "Sticky with fat" , "Like the pole that is hard to climb" , "Sycophantic" .)