Too short to grip old king keen on enlightenment? (3,4)
I believe the answer is:
all ears
'keen on enlightenment?' is the definition.
(someone who is 'all ears' is eager to learn)
'too short to grip old king' is the wordplay.
'too' becomes 'also' (synonyms).
'short' means to remove the last letter.
'to grip' indicates putting letters inside.
'old king' becomes 'lear' (legendary King of England).
'also' with its final letter taken off is 'als'.
'als' enclosing 'lear' is 'ALL EARS'.
(Other definitions for all ears that I've seen before include "Prepared to listen" , "Listening attentively" , "Very alert" , ".Listening very intently" , "description of cornfield?" .)