Enter uninvited because of genuine diamonds inside (7)
I believe the answer is:
intrude
'enter uninvited' is the definition.
(an intruder enters without permission)
'because of genuine diamonds inside' is the wordplay.
I cannot quite understand how this works, but
'diamonds' could be 'd' (abbreviation in bridge say) and 'd' is present in the answer.
'genuine' could be 'true' (associated in meaning) and 'true' is found within the remaining letters.
'inside' could be 'in' and 'in' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for intrude that I've seen before include "Push in where not wanted" , "Enter uninvited and unwelcome" , "Come in without invitation" , "Break in" , "Stick one's nose in" .)