Continuous acceleration in ship (6)
I believe the answer is:
linear
'continuous' is the definition.
Both the definition and answer are adjectives. Maybe you can see a link between them that I can't see?
'acceleration in ship' is the wordplay.
'acceleration' becomes 'a' (symbol used in Physics e.g. f=ma).
'in' means one lot of letters goes inside another.
'ship' becomes 'liner' (as in an ocean liner).
'a' put within 'liner' is 'LINEAR'.
Can you help me to learn more?
(Other definitions for linear that I've seen before include "-- Motor; -- equation" , "Of a line or length" , "Measured lengthwise" , "Long and narrow, of one dimension" , "following straight path" .)