A lot of water right in the glass (7)
I believe the answer is:
breaker
'a lot of water' is the definition.
I can't judge whether this defines the answer.
'right in the glass' is the wordplay.
'right' becomes 'r' (common abbreviation).
'in the' is an insertion indicator.
'glass' becomes 'beaker' (I've seen this before).
'r' going into 'beaker' is 'BREAKER'.
Can you help me to learn more?
(Other definitions for breaker that I've seen before include "White-topped wave" , "Heavy wave arriving on the shore" , "Large sea wave" , "Wave with white crest" , "Wave hitting the shore" .)