Next to order one is glad (9)
I believe the answer is:
alongside
'next to' is the definition.
(I've seen this before)
'order one is glad' is the wordplay.
'order' indicates an anagram.
'one'+'is'+'glad'='oneisglad'
'oneisglad' anagrammed gives 'ALONGSIDE'.
(Other definitions for alongside that I've seen before include "Next to, another boat perhaps" , "Parallel to" , "Bordering" , "next door" , "Lying next to, as a boat might be" .)