Modern aircraft essentially have facility to become smaller (8)
I believe the answer is:
decrease
'become smaller' is the definition.
(I've seen this before)
'modern aircraft essentially have facility' is the wordplay.
'modern' becomes 'de' (I can't explain this - if you can you should give a lot more credence to this answer).
'essentially' indicates the central letters.
'have' means one lot of letters go next to another.
'facility' becomes 'ease' (facility can mean ease or absence of difficulty).
The middle letters of 'aircraft' are 'cr'.
'de'+'cr'+'ease'='DECREASE'
'to' is the link.
Can you help me to learn more?
(Other definitions for decrease that I've seen before include "Peter out" , "Get less" , "Reduce, lessen" , "Abate, diminish" , "Plummet" .)