Plan in relation to Channel Islands gym (6)
I believe the answer is:
recipe
'plan' is the definition.
(thesaurus)
'relation to channel islands gym' is the wordplay.
'relation' becomes 're' (re is a kind of relation).
'to channel islands' becomes 'ci'.
'gym' becomes 'pe'.
're'+'ci'+'pe'='RECIPE'
'in' acts as a link.
(Other definitions for recipe that I've seen before include "Method for cooking" , "Directions for making food etc" , "Cook's instructions" , "Kitchener's instructions" , "Directions for cooking the turkey e.g." .)