See through end of telescope in port after it's set up (4,4)
I believe the answer is:
tide over
'see through' is the definition.
(both mean to sustain in a difficult period)
'end of telescope in port after it's set up' is the wordplay.
'end of' says to take the final letters.
'in' is an insertion indicator.
'port' becomes 'dover' (I've seen this before**).
'after' is a charade indicator (letters next to each other).
'set up' says the letters should be written in reverse.
The last letter of 'telescope' is 'e'.
'it' back-to-front is 'ti'.
'e' going within 'dover' is 'deover'.
'deover' put after 'ti' is 'TIDE OVER'.
(Other definitions for tide over that I've seen before include "Support (someone through a bad patch)" , "help in hard times" , "Help (someone) through a difficult period" , "to cope with temporary problem" , "give temporary help" .)