Grandma, it seems, is less than magnanimous (3)
I believe the answer is:
nan
'grandma' is the definition.
(nan can informally mean a grandmother)
'less than magnanimous' is the wordplay.
'less' says the answer is hidden in the clue (the clue less some of the letters in it).
'NAN' can be found hidden inside 'than magnanimous'.
'it seems is' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for nan that I've seen before include "Gran" , "A relative (colloq.); unleavened bread" , "Ancestor" , "Grannie" , "Darling dog" .)