It gives height in flight (5)
I believe the answer is:
riser
This might be a double definition.
'it' is the first definition.
The definition suggests a singular noun which matches the answer.
'height in flight' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'gives' acts as a link.
Can you help me to learn more?
(Other definitions for riser that I've seen before include "found on the staircase" , "Vertical upward pipe" , "He gets up" , "Upright part of step - vertical pipe" , "Vertical pipe in a building" .)