To start grumbling at spilt tea is maybe too much (5)
I believe the answer is:
great
'too much' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?
'to start grumbling at spilt tea is maybe' is the wordplay.
'to start' indicates taking the first letters.
'at' says to put letters next to each other.
'spilt' becomes 'r' (I am not sure about this - if you are sure you should believe this answer much more).
'is maybe' indicates an anagram.
The initial letter of 'grumbling' is 'g'.
'tea' is an anagram of 'eat'.
'g'+'r'+'eat'='GREAT'
Can you help me to learn more?
(Other definitions for great that I've seen before include "Considerably above average" , "Large, fantastic" , "Large; fine" , "Very good, excellent" , "Of major significance - very good" .)