Rambling is so grand, but you may need these directions (4,5)
I believe the answer is:
road signs
'you may need these directions' is the definition.
(road signs usually have directions on them)
'rambling is so grand' is the wordplay.
'rambling' is an anagram indicator.
'is'+'so'+'grand'='issogrand'
'issogrand' is an anagram of 'ROAD SIGNS'.
'but' is the link.
(Other definitions for road signs that I've seen before include "pointers" , "Indications for car driver to observe" .)