Moody chap is more disposed to get tense (11)
I believe the answer is:
atmospheric
'moody' is the definition.
(I've seen this before)
'chap is more disposed to get tense' is the wordplay.
'disposed' indicates an anagram.
'to get' means one lot of letters goes inside another.
'tense' becomes 't' (abbreviation used in many dictionaries).
'chap'+'is'+'more'='chapismore'
'chapismore' with letters rearranged gives 'amospheric'.
'amospheric' going around 't' is 'ATMOSPHERIC'.
(Other definitions for atmospheric that I've seen before include "(Of a place) having a perceptible feeling" , "background" , "Creating a mood, emotion" , "conveying a certain air" , "Evoking feelings or emotions" .)