Devout head of Giggleswick strangely lacking in heart (5)
I believe the answer is:
godly
'devout' is the definition.
(I've seen this before)
'head of giggleswick strangely lacking in heart' is the wordplay.
'head of' says to take the initial letters.
'strangely' becomes 'oddly' (synonyms).
'lacking in heart' says to hollow out the word (remove centre letters).
'oddly' with its middle removed is 'odly'.
The first letter of 'giggleswick' is 'g'.
'g'+'odly'='GODLY'
(Other definitions for godly that I've seen before include "Religious, pious" , "Devout" , "Divine" , "Pious, decent" , "Reverential" .)