Buggy memory on laptop, ultimately (4)
I believe the answer is:
pram
'buggy' is the definition.
(a buggy for children)
'memory on laptop ultimately' is the wordplay.
'memory' becomes 'ram' (RAM is an example).
'on' means one lot of letters go next to another.
'ultimately' suggests the final letters.
The final letter of 'laptop' is 'p'.
'ram' after 'p' is 'PRAM'.
(Other definitions for pram that I've seen before include "Baby vehicle" , "A common baby carriage" , "accommodation for child" , "Nanny may use this" , "Ramp for a baby buggy" .)