Beetle Scottish landowner catches returning by day (8)
I believe the answer is:
ladybird
'beetle' is the definition.
(I know that ladybird is a type of beetle)
'scottish landowner catches returning by day' is the wordplay.
'scottish landowner' becomes 'laird' (I've seen this before).
'catches' indicates putting letters inside.
'returning' is a reversal indicator.
'day' becomes 'd' (abbreviation for day).
'by'+'d'='byd'
'byd' written backwards gives 'dyb'.
'laird' placed around 'dyb' is 'LADYBIRD'.
(Other definitions for ladybird that I've seen before include "old children's book" , "spotted one that flies" , "that's spotted in gardens" , "Black-spotted red beetle" , "This insect likes greenfly" .)