How the grit can possibly be compacted (7)
I believe the answer is:
tighter
'possibly be compacted' is the definition.
I can't judge whether this definition defines the answer.
'how the grit' is the wordplay.
'how' is an anagram indicator (I've seen this in other clues).
'the'+'grit'='thegrit'
'thegrit' with letters rearranged gives 'TIGHTER'.
'can' is the link.
Can you help me to learn more?
(Other definitions for tighter that I've seen before include "more closely" , "More close-fitting" , "even more tense" , "Less loose" , "more mean" .)