Big profit this person's invested in case of trouble, being a waiter? (7,4)
I believe the answer is:
killing time
'a waiter?' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'big profit this person's invested in case of trouble' is the wordplay.
'big profit' becomes 'killing' (I can't explain this - if you can you should give a lot more credence to this answer).
'this person's' becomes 'I'm' (('I am' - 'this person' means the crossword setter).
'invested in' is an insertion indicator.
'case of' means to remove the middle letters (like emptying a case).
'trouble' with its middle removed is 'te'.
'im' inserted within 'te' is 'time'.
'killing'+'time'='KILLING TIME'
'being' acts as a link.
Can you help me to learn more?
(Other definitions for killing time that I've seen before include "Occupying oneself to avoid boredom" , "Filling in spare moments" , "Finding idle amusement - perhaps" , "Occupying oneself to pass hours" .)